I'll never pay more than £30 ($50) for a game, and even that is very rare. It's got to be something I've been waiting for more than anything else for years, like S.T.A.L.K.E.R., Deus Ex 3, Syberia 3 or Dreamfall Chapters.
Anything else, I'll wait for it to drop below £15 ($25).
I have over 100 games on Steam, and they're mostly old or indie titles that I got for £7 ($10) or less, or more recent games that I got in the sales at 75% off or something awesome like that.
Note than over here, the prices include sales tax, too.